DEVELOPMENT AND IN VITRO CHARACTERIZATION OF NANOEMULSION EMBEDDED THERMOSENSITIVE IN-SITU OCULAR GEL OF DICLOFENAC SODIUM FOR SUSTAINED DELIVERYAbstract
The objective of this work was improvement in the ocular bioavailability of diclofenac sodium by enhancing drug permeation across cornea and promoting drug retention time on ocular surface. Using pseudo ternary phase diagrams transparent regions were identified and nanoemulsions were prepared by self-emulsification method, which were further optimized by emulsification study and drug content. Three best NE formulations were incorporated in 20% poloxamer 407 (thermosensitive polymer solution) to formulate nanoemulsion embedded thermosensitive in-situ ocular gel and further evaluated on the basis of gelation temperature and drug entrapment. Optimized nanoemulsion formulation was evaluated by TEM, particle size analysis and zeta potential. The optimized NE gel formulation changed from sol-gel phase at physiological temperature. Comparison of dissolution profile of developed formulation was carried out with the marketed formulation. The formulated NE in-situ gel showed drug release for a longer duration of time as compared to the marketed eye drops (0.1% w/v Voltaren Ophtha). The in-vitro release data was fitted to various kinetic models. It was found that the in-vitro drug release of diclofenac sodium nanoemulsion thermosensitive gel was best explained by zero order. In-vitro transcorneal permeation study was carried out on isolated goat cornea and comparison was done with marketed formulation, which showed that developed formulation exhibited higher permeation across goat cornea in 4 hours (44.65%) compared with that of the marketed formulation (31.25%). Hence this novel formulation was found to be a good replacement for conventional eye drops due to higher permeation and prolonged precorneal residence time.